In recent years, social networking service (hereinafter, referred to as “SNS”) technologies have been widely used as represented by Twitter (Registered Trademark), Facebook (Registered Trademark), and the like. In such an SNS, for example, users can exchange messages such as in chats or the like and establish friend relationships on the network. Thereby, connections between the users are created. Under such circumstances, in recent years, it is well known that the concept of a social graph to depict such connections between users has been proposed in Facebook.
As represented by Facebook described above, such a social graph is constructed by behavior of users in a predetermined SNS in general. A technology of collecting social graph information through different web services, creating a synthetic social graph from the collected social graph information, and delivering the social graph has been disclosed (Patent Document 1).
Moreover, in recent years, an operating environment (application platform) such as an application program interface (API) to be operated on a web browser has been provided onto an SNS. Application software created with this as platforms are collectively referred to as social applications, and games in the social applications are referred to as social games.
In particular, social games do not require dedicated client software but can be played with only a web browser and an account of an SNS, and the most remarkable characteristics of social games include combination with the original communication function of an SNS. The games themselves are mainly easily playable in a short period of time not only on a personal computer but also on a feature phone, a smart phone, and the like.